Many of the aged or infirmed have difficulty walking because they have weak legs or poor balance. In order to help these people remain independently mobile, various walking devices have been developed that allow the user to support his weight at least partially with his arms.
The open walking frame or walker is such a device. Walkers generally consist of four legs attached by some form of square frame with at least one side open so that the user can stand within the four legs. The frame has handles so the user can pick up the walker, set it in front of him, and lean on it as he walks forward. In this way, the user can support some of his weight with his arms and shoulders. Further, the user can balance his weight more easily by shifting his weight to the different sides of the walker.
Walkers have been developed that fold into a small space so that they can be more easily stored when not in use. See, for example, U.S. Pat. Nos. 3,945,389, 3,658,079, 3,993,088, 4,180,086 and 4,298,016. In these patents, the walkers are comprised of 3 frames, one in the front and one on each side. The user steps into the frame from the rear. When the walker is not being used, the side frames can each be rotated onto the front frame of the walker to reduce storage space. The side frames are locked in the open position by various mechanisms.
The folding walker shown in U.S. Pat. No. 3,945,389 employs a brace extending from a rear leg to a front leg of the side frame. The locking mechanism consists of a sliding pad that is pinned onto the side frame at a single point on the bottom of the brace. The sliding pad is slidingly mounted onto the front frame by a front pin, which moves along in a notch in the sliding pad as the side frame is opened and closed. A detent is mounted on the front frame. As the side frame is opened, the detent pin slips into a hole on the sliding pad and thereby prevents the pad from sliding about the front pin. Thus, the side frame is prevented from opening or closing by the sliding pad. To unlock the sliding pad, the user must reach from the handle on the side frame to a small tab on the sliding pad at the front frame to depress the detent pin. This tab is located in front of the front foot of the walker.
The folding walker shown in U.S. Patent No. 4,298,016 employs a notched rod that is pinned at a single point onto the side frame at the bottom of a brace on the side frame. This rod fits within a spring-biased housing that is mounted on the front frame. When the side frame is opened to the proper position, the housing latches onto the notch in the rod, keeping the rod from moving and thereby preventing any further rotation by the side frame. To fold the walker, the user must reach from the handle on the side frame to the housing on the front frame, depress it (thus releasing the rod) and simultaneously close the side frame.
Other folding walkers have locking means consisting of telescoping rods attached to the front and side frames or detents mounted on the legs of the walker that prevent the legs from rotating.